.
.
| Fig.
39: An adult soil mite, greatly magnified and color- enhanced using
a scanning electron microscope. In reality, this tiny arachnid is
under
1 mm in length. |
|
Section
3 - Substrate pests
(a - soil mites)
Class
- Arachnida
Order
- Acari
Size:
1 mm to sub-microscopic
Soil mites (fig.
39) are enemy #1 to the beetle breeding hobbyist, and, omnipresent as these
tiny creatures are, your chances of having some trouble with them are virtually
assured. |
|
| These tiny arthropods
occur anywhere there is moist organic matter, and can become a major problem
in rearing substrate. The main reason that this happens is due to
the highly nutritious composition of the additives which are placed into
the substrate to serve as food for the scarab larvae, primarily dry dog
food. In as little as 10 days, just a few mites can explode into
plague proportions when conditions are suitable. It is highly unfortunate
that the very conditions that create an optimum environment for rearing
scarab larvae are also just right for soil mites. Generally, it is
not the adult mites which create a problem for scarab larvae (although
the mites can cause dog food to spoil and decompose
much more rapidly
than normal). Rather, it is the much smaller juvenile stage of the
mites which constitute a threat. When there is an abnormally large
quantity of young mites present in the substrate, they have a strong tendency
to adhere to the bodies of the scarab larvae. Whether they are merely
using the larva as transport or are actually parasitizing the larva is
not very well understood. They appear as pinkish, encrusting blotches
which are most commonly seen around the skin folds of the larva, especially
on the ventral side (fig. 51). Each mite is only about the size of
a tiny grain of sand, but as they accumulate, they can cover large areas
of the larva's skin, giving the larva the appearance of having been rolled
in wet sand. In extreme infestations, the larva can be at risk of
having its breathing spiracles and mouth parts blocked (fig. 52), leading
to ill health and even death. Obviously, commercially available mite-killing
agents (such as are used to treat mites of pet snakes)
cannot
be used to treat infestations on arthropods, as these chemicals will just
as readily kill your insects as it will the mites. Although virtually
impossible to eliminate entirely, there IS fortunately a way
to keep the numbers of these pests in check, and it works quite well if
done routinely. The best way to cope with an infestation of mites
is to simply transfer your larvae into a fresh mixture of substrate.
Whenever you notice a lot of mites (either adults or larvae) be sure to
change your substrate. Afterward, be as conservative as possible
about how much dog food you place into the substrate as a food supplement,
and do not give your larvae any more dog food than they can completely
consume in one week. |
|
.
| Fig.
40: A 3rd instar Chelorrhina polyphemus confluens larva afflicted
with a heavy infestation of larval mites. The mites are visible as
a fine, sand-like encrustation present at or near the larva's skin folds.
In the event of such an incident, the best way to treat the problem is
at its source - the substrate itself. Trying to remove mites mechanically
by brushing or rubbing them off the larva is not advised, as this will
only traumatize the larva and abrade its skin. By no means ever attempt
to SCRUB the larva with a brush and water, because even though this may
effectively remove most of the mites, it will also severely stress the
larva. |
.
.
| Fig.
41: A close up view of the same C. polyphemus larva pictured above.
At this range, the individual mites are more plainly visible. Note
that the scarab larva's breathing spiracles are becoming at risk of being
blocked by this rather severe mite infestation. Regular substrate
changes should work well to prevent mite numbers from becoming too high.
However, one cannot expect to ever be completely rid of these extremely
persistent pests once they become established. |
|
|
.
|
| (b
- phorid flies)
Class
- Insecta
Order
- Diptera
Family
- Phoridae
Size:
2-3 mm
Phorid, or "hump-backed"
flies (fig. 42) should never be allowed to be present in any numbers whatsoever.
Also called humpbacked flies, phorid flies belong to the family Phoridae,
which contains many species, is worldwide in distribution and occur in
virtually all environments. Adult flies are about one-sixteenth to
one-eighth inch long and move with a characteristic short, jerky, nervous
walk or flight. |
|
| They are dark tan
to almost black with a humpbacked appearance. The large segment (femur)
of the hind legs is distinctly flattened laterally (fig. 43). In
the home, this fly lays eggs on, and larvae develop in, moist, decaying
organic matter such as rotting fruit, vegetables or meat, wet soil high
in organic matter around potted plants, garbage disposals and floor drains.
Phorid flies also may become pests in commercial kitchens, hospitals and
even mausoleums.
The best line of
defense against phorids lies in maintaining very strict hygiene standards.
If your enclosures are kept quite clean, you should not have any problems
from phorid flies. The main way that phorids become established in
scarab enclosures is from the fruit that is fed to the adult scarabs.
Bananas are a favorite food of many rhinoceros beetles, but unfortunately,
it is also a perfect material in which phorid maggots can develop.
Make sure that a piece of fruit is never left inside the enclosure for
any longer than 24 hours. Old fruit should be sealed up in a plastic
bag and disposed of properly to prevent any flies from developing in it.
In just a matter of hours, a large rhinoceros beetle can reduce soft fruits
such as banana can be reduced to a slushy, hard to clean up mess which
can drain liquid into the substrate, so if possible, you may want to consider
placing your fruit on a special feeding dish onto which the adult beetles
can easily crawl. This will help avoid soiling of the substrate with
juice and liquefied fruit, thus helping to avoid attracting phorid flies. |
|
.
| Fig.
43: A line drawing of a typical phorid fly to better illustrate its morphological
characteristics. Cosmopolitan in distribution, these flies are commonly
encountered most everywhere, and can breed in any moist organic
material. Spoiled fruit inside terraria used to house scarab beetles
and other invertebrates is a common breeding site for these flies.
Thus, uneaten fruit should be removed within 24 hours. |
|
.
| Fig.
44: A roll of sticky fly tape - very useful for capturing phorids
and other species of flies which may become a nuisance. |
|
As
a preventative measure, I would strongly suggest that you always keep several
sticky fly tapes (fig. 44) hanging from the ceiling around your scarab
rearing area. They are available in many stores. These traps
are completely NON-TOXIC and for some reason, they are positively irresistible
to flies of all types, especially phorids. These simple devices consist
of nothing more than an expandable strip of thick paper coated with an
extremely viscous, rosin-rubber compound. They are a very strong
line of defense against fly infestation. After several flies have
become stuck, they act as an attractant to other flies. Apparently,
when flies see other members of their own species gathered on an object,
they are led to believe that it is a feeding site. By they time they
land to investigate, they have already become trapped themselves.
| Fig.
45: Another photo of a phorid fly. These flies are extremely
common, and the only means of controlling them is by ensuring good sanitation
standards are continually in effect within your beetle terraria.
Always be sure to remove any uneaten fruit before it has opportunity to
spoil and serve as a breeding site, and most certainly never leave the
body of a deceased beetle in an enclosure for ANY length of time, as dead
arthropods can serve as OPTIMUM breeding sites for these pests. |
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